A.R.
I had the same feeling when my now 23 month old son wouldn't transition easily. It was the biggest battle thus far, and I thought it would never end! I, too, gave in and would hand him the bottle when he refused to try the cup. It was the only way he would get his daily milk/fluid intake.
One day, I realized that he was accepting the sippy cups every time I gave them to him and I hadn't even noticed! I promptly threw away all of his bottles that very day.
Hang in there, be persistent, but don't take the bottle away until that day comes for you as it did for us, if you are worried about fluid intake. It WILL work, eventually!